FI-2460: Support for HL7 validator wrapper

[dehall]

This PR enables support for the the g10-test-kit to use the original Inferno validator wrapper or the HL7 validator wrapper, toggled by the env var USE_HL7_RESOURCE_VALIDATOR. From the user perspective, there should be no visible change. If I've done this right then it should be plug & play.

Summary of changes:

• Add HL7 validator service to docker-compose and nginx, commented out by default
• Change validator block in test suite to a conditional that selects validator or fhir_resource_validator based on a new env var USE_HL7_RESOURCE_VALIDATOR. Add igs setting to this block if using the HL7 validator.
• Add a cli_context block to specify validator settings:
  • txServer nil disables use of a TX server. Aligns with DISABLE_TX env var in the inferno validator
  • displayWarnings true sets any "display issue" messages to be warnings instead of errors. Aligns with DISPLAY_ISSUES_ARE_WARNINGS env var in the inferno validator
  • disableDefaultResourceFetcher true disables fetching and validating against any unknown profiles found in a resource. (This is now a default in inferno-core, not yet released though. No harm in keeping this setting here temporarily or forever)
• Change version endpoint and expected version. (HL7 validator wrapper reports version as the the https://github.com/hapifhir/org.hl7.fhir.core release number)
• Ignore "URL does not resolve" errors - these were ignored natively in the Inferno validator but the mechanism to do that isn't exposed in the HL7 wrapper
• Ignore "[No server available]" errors - these were introduced somewhere in the core validator between versions 6.2.8 and 6.3.0 and occur when txServer is disabled. See screenshot below.
• Update spec tests; see notes on #497

New error messages that need to be ignored -- there are two messages that occur per usage of a mime type (CapabilityStatement, DocumentReference, some uses of DiagnosticReport)

[dehall]

How will the "two suites" approach look from a user perspective? Will we show the two suites on the start page and the user has to pick one? In the meantime I'll press forward with cleanup here and then adding hl7 validator support to the other two test kits.

[Jammjammjamm]

How will the "two suites" approach look from a user perspective? Will we show the two suites on the start page and the user has to pick one?

We'll want to discuss that with @arscan